Jupiter is the fifth planet from the Sun and most massive planet in our solar system. Named after the Roman ruler of the gods and heavens, Jupiter is larger than all the other planets combined. It has 1,400 times the volume of Earth but only 318 times more mass, indicating that it must consist of gas rather than the metals and rocks of which the Earth is composed of. Given the planet’s large proportion of hydrogen and its huge mass, it has been traditional to assume that Jupiter formed by condensation from the primordial solar nebula.

The composition of Jupiter’s atmosphere is mostly hydrogen and helium. It’s appearance is a tapestry of beautiful colors and features. The planet has an internal heat source; it emits more energy than it receives from the Sun. Jupiter was the first planet found  to be a source of radiation at radio wavelengths. The radiation was recorded in 1955 at a frequency of 22 megahertz in the form of noise bursts. The bursts of radio noise from three distinct areas constituted the first evidence for a Jovian magnetic field.

The pressure in Jupiter’s deep interior is so high that the hydrogen there exists in a fluid metallic state. This allows Jupiter to have the strongest magnetic field of any planet. The powerful magnetic field is driven by Jupiter’s fast rotation and at it’s center, the immense pressure may support a solid core. The core is thought to consist of heavier elements at such high temperatures (20,000 K) and pressures that their properties are not yet understood.

Jupiter has powerful storms. These storms are a result of moist convection in the atmosphere connected to the evaporation and condensation of water. Jupiter’s largest, most prominent, and longest-lived storm is known as the The Great Red Spot. Akin to a hurricane on Earth, the storm has been observed for over 300 years. The storm is approximately 12,400 miles long and 7,500 miles wide which is large enough to engulf Earth and Mars side by side. The persistence of the Great Red Spot is related to the fact that it never comes over land and doesn’t encounter friction and is powered by Jupiter’s internal heat source. The storms  red coloration is unknown; suggestions range from compounds of sulfur and phosphorus to organic material.

Four of Jupiter’s moons were among the first objects in the solar system ever discovered by means of a telescope . Galileo first saw the mons in 1610, now called the Galilean satellites. The planet now has 67 confirmed moons which physical and orbital characteristics vary widely.

One of the more fascinating of Jupiter’s moon is called Europa. Slightly smaller than the Moon, it is primarily made of rock and most likely has an iron core with an atmosphere composed primarily of oxygen. Most planetary scientists believe that a layer of liquid water exists beneath Europa’s surface. It’s most striking surface features are a series of dark cracks crisscrossing the planet, called lineae. The cracks move relative to each other may be produced by a series of eruptions of warm ice as the Europan crust spread open to expose warmer layers beneath. The effect would have been similar to that seen in Earth’s oceanic ridges.

Jupiter also has the largest satellite in our solar system. Discovered by Galileo and Marius in 1610, Ganymede is larger than Mercury and Pluto. If it orbited the sun instead of orbiting Jupiter, it would easily be classified as a planet.

Jupiter has been explored by several robotic spacecraft over the years. It was visited by NASA’s Pioneer 10 spacecraft in December 1973, and then by Pioneer 11 in December 1974. Then by the Voyager 1 and 2 spacecraft in 1979. After a long break the Ulysses spacecraft flew by in 1992 and in 1995 the Galileo orbiter became the first spacecraft to orbit Jupiter. It launched the first probe into Jupiter, directly measuring its atmosphere.

Jupiter Facts

  • If you weigh 100 pounds on Earth, you would weigh 264 pounds on Jupiter.
  • Jupiter’s volume is large enough to contain 1,300 planets the size of Earth.
  • Jupiter has the biggest moon in the Solar System, Ganymede. It is even bigger than Mercury and Pluto.
  • Unlike other planets, Jupiter sends out a strong radio radiation that can be detected on Earth.
  • Jupiter is the third brightest object in the solar system – It is one of five planets that can be seen with the naked eye, the others are Mercury, Venus, Mars and Saturn.
  • Jupiter is the fastest spinning planet in the Solar System.
  • The Clouds on Jupiter are 25 miles thick.
  • The rings around Jupiter were the third set of rings discovered in the Solar System, after Saturn and Uranus.
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